My 13 year old is the same way, and so is my 12 year old. I have no advice, Im trying to get mine to understand they have to turn the stuff in too. I basically told both of mine that if they don't do the work they're in trouble and if they do the work and dont turn it in and get a bad grade they're in trouble..so far this week they've turned everything in (this was prompted after I got progress reports from both showing they're either not doing it at all or not turning it in).